1. Field of the Invention
The present invention relates to a substrate cleaning method and a substrate cleaning apparatus, which are used to clean semiconductor wafers, substrates for flat panel displays (FPDs) such as glass substrates for liquid crystal displays (LCDs), and substrates for other devices.
2. Description of the Related Art
In a semiconductor device manufacturing process, a semiconductor wafer (hereafter, simply referred to as wafer) is cleaned using a predetermined chemical (cleaning liquid), and a cleaning process of removing a polymer and the like after contamination and etching processes of particles, organic contaminants, metal impurities and the like adhered to the wafer is then carried out.
A sheet-fed wafer cleaning apparatus that carries out a chemical process by holding the wafer on a spin chuck, supplying a chemical onto the front and back surfaces of the wafer either at rest or spinning, supplies a rinsing liquid such as purified water onto the wafer while spinning the wafer at a predetermined rotational rate so as to wash away the chemical, and then carry out a drying process while spinning the wafer is known as such wafer cleaning apparatus for carrying out that cleaning process.
As such a sheet-fed wafer cleaning apparatus, in the case of cleaning using a hydrofluoric acid chemical, for example, the rinsing liquid in the periphery of the wafer may be shaken off in a short period by centrifugal force since the wafer front surface is hydrophobic; however, the timing of shaking off the rinsing liquid at the wafer center where the centrifugal force is small is delayed, and thus watermarks may generate in the wafer periphery that has already dried while shaking off the rinsing liquid at the center. In addition, liquid drops may remain at the wafer center, causing particle generation.
In order to resolve such disadvantages, a technology scanning from the substrate center out towards the peripheral portion using a nozzle that sprays purified water and a nozzle that sprays inert gas is disclosed in Japanese Patent Application Laid-open No. 2001-53051. Such configuration allows nearly simultaneous progression of wetting the substrate with sprayed purified water, removing a purified water film using sprayed inert gas, and removing a water film from the substrate by rotational centrifugal force, and since it dries from the substrate center out towards the periphery spreading out in an approximate concentric circle, watermarks and contamination are prevented.
However, with such technology, since the wafer or substrate is basically spun at a high speed when drying, rinsing liquid may rebound from a chamber or the like of the apparatus at this time, and water drops may adhere to dried parts of the wafer, leading to particles and the like.
Furthermore, while there are various product wafers such as ones with patterns formed thereon or various films formed thereon, and a cleaning process in which generation of particles on various wafers having such hydrophobic parts is sufficiently suppressed is desired, however, adequate results are not yet necessarily achieved so far.